Since the 1970s, the surface area of live coral on reefs has decreased from over 50 percent to 8 percent in recent times, according to NBC News.

The IUCN calls the situation "appalling," noting that "extraordinary advances have been made in the documentation for the status and trends of tropical forest ecosystems around the world."

The study, which 360 experts contributed to, explains that coral in the Florida Keys, Puerto Rico, and U.S. Virgin Islands "has progressively declined from 25 to 35 percent in the 1970s to less than 15 percent today."

"Corals declined precipitously on the Jamaican north coast in the 1980s ... but not at Curacao and Bonaire where coral has more gently declined to about 25-30% today," the study states.

NBC points out that coral bleaching has contributed to the problem. The site describes bleaching as "a process triggered by stress such as warm seas or pollution whereby the coral expels the tiny single-celled algae inside that provides its color."

So what can be done to combat the problem? The IUCN asserts, "Looking forward, there is a desperate need for coral reef ecologists and managers to develop a universal standard for monitoring the ecological status and trends of coral reefs."

Marine biologists Jason Bruno, who worked on the IUCN study, offers his expertise: "Our preliminary analysis suggests that the state of Caribbean reefs continues to worsen, primarily due to ocean warming. To reverse this dire trend, job one is to halt the increase of greenhouse gas emissions."